Blagg



7 FLEXIBLY COUPLED WELL. TOOLS Filed Aug. 8. 1961 Zea/7 B/ayy INVENTOR.

United States Patent 3,128,825 FLEXEBLY CUUPLED WELL TOOLS Leon Blagg, Channelview, Tex., assignor to Schlumberger Weill Surveying (Iorporation, Houston, Tex., a corporation of Texas Filed Aug. 8, 1961, Ser. No. 139,072 4 Claims. (Cl. 166-55) The invention relates to well tools and, more particularly, to well completion apparatus arranged for passage through small diameter strings of pipe wherein such apparatus may have considerable length and wherein the string of pipe is expected to have bends or curvatures along its length which might prohibit the passage of apparatus therethrough.

A recently developed techique in well production is the so-called multiple completion of wells wherein a plurality of strings of tubing each having relatively small diameter are cemented or otherwise disposed in a well bore. The tubing strings generally extend to different production zones and perforating of the tubing strings independently of interference with adjacent strings is desirable. In actual practice it has been found that one or more tubing strings may have a somewhat spaghetti-type of configuration along the length of a bore hole which prevents or impedes the passage of elongated well tools therethrough. The incompatability between a relatively long and rigid tool with little flexibility and the curvature or bends in long strings of tubing has presented problems which are not easily solved. For example, to further reduce the diameter of an apparatus relative to a small diameter string of tubing is generally expensive and generally introduces undesirable limitations in the apparatus. For example, in perforating devices, a reduction in diameter generally reduces operational and performance characteristics. Hence, it is generally desirable not to reduce the diameter of a tool below a maximum dimension necessary to pass through a relatively straight tubing string.

Therefore, it has been proposed to use a universal type of joint or coupling to provide a pivotal coupling between sections of a tool and hence break up the long rigid sections of tool into relatively short sections which can better accommodate themselves to the various twists and turns which the tubing might take. In this way a relatively long tool can be passed through relatively tortuous tubing strings being limited only by the length of the longest section of the tool relative to the greatest curvature in a tubing string. However, it will immediately be apparent that electrical conductors passed from section to section of the tool must bypass the universal joint and be exposed to the corrosive effects of well fluids. It is also necessary that the entry and exit of the conductors from the housing sections must be fluid and pressure tight. The deleterious effects of corrosive fluids under pressure precipitate malfunctions of the tool and, hence, are generally undesirable.

Accordingly, it is an object of the present invention to provide a new and improved elongated well tool in which sections of the tool are flexibly connected to one another along its length with the interior of the tool isolated from contact with well fluids over its entire length.

Another object of the present invention is to provide new and improved jointed tool wherein pressure sealed conduits are provided between joined sections of the tool.

Apparatus in accordance with the present invention includes a well tool having a plurality of housing sections with adjacent housing sections flexibly coupled to one another. The flexible coupling for adjacent housing sections includes a tubular coupling member with an elongated flexure section sealingly coupled to the respective ends of two adjacent sections of the tool, the coupling member having a relatively small diameter compared to the diameter of the sections to be coupled. A safety.

sleeve may be concentrically disposed about the coupling member and loosely attached relative to the adjacent housing sections to permit limited flexing of the coupling member relative to one another and couple the housing sections to one another should the coupling member fail.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a view of a well tool in which the present invention is embodied;

FIG. 2 is a view shown in partial cross-section along the length of a coupling unit embodying the present invention; and

FIG. 3 is a view taken along line 3-3 of FIG. 2.

A well tool 10 as shown in FIG. 1, is arranged for use in a small diameter tubing string such as would be found in a multiple well completion and wherein tortuous configurations of the tubing string are expected. A cable 11 is typically connected to a connector head 12 and the tool further may include a casing collar locator 13, an indexing device 14, a first radioactivity section 15, a second radioactivity section 16, and at the bottom of the tool a directional perforating device 17. Tool 19, in use, may be lowered into one of a number of adjacent tubing strings to a level or zone where perforation of the one tubing string is desired to provide communication between the earth formations and tubing string. At the level to be perforated, springs 2i on the indexing device 14- are in frictional engagement with the interior of tubing string and the indexing device 14 permits manipulation of the tool to rotate the radioactivity sections 15 and 16 as well as the perforating device 17 relative to the tubing. The radioactivity section 15 can include means to directionally detect radioactivity relative to adjacent strings of tubing while section 16 can include a radioactivity source. Hence, with the detection of adjacent strings of tubing, the perforating gun 17 may be positioned in a selected rotative position relative to the adjacent tubing strings. The foregoing briefly described apparatus as well as its operation techniques will not be further described herein since such description is not germane to the present invention and since such apparatus is known to those skilled in the art of multiple well completion tools. Insofar as the present invention is concerned, tool 10 is made up of a number of housing sections which are joined to one another by a flexible connection permitting flexure of adjacent housing sections relative to one another.

The flexible connection 21 as shown more specifically in FIG. 2 includes a tubular coupling member 24 composed of steel which is threadedly received within the respective central bores of the exemplary housing sections 15 and 16. An end of a housing section, housing 15 for example, is typically provided with a counter bore 26 at the end, a smooth bore section 27, and a threaded section 28. The coupling member 24 is provided with threaded end sections 29 and 30 with adjacent annular grooves 30a which receive 0 rings 31 or any other suitable packing material. Hence, one end of a coupling member 24 may be threadedly connected into an end of a housing section with the O ring 31 providing a fluid and pressure seal therebetween. The section 24a of the coupling member 24 intermediate of its threaded ends 29 and 30 is reduced in diameter relative to the diameter of an adjacent housing section and has a relatively thin wall as compared to its diameter. This provides an effective pressure resistant section between the housing sections. The length of the section 24a relative to its diameter is such that the coupling member 24 will have an adequate degree of fiexure when adjacent housings are tilted relative to one another. From the description thus far it will be seen that two housing sections and 16, for example, can be connected to one another in a fluid tight relationship while the interior of the coupling member 24 permits the passage of conductors therethrough without exposing the conductors to the effects of the well fluid. The relatively long section 24a of the coupling member 24 permits tilting of the two housings relative to one another. Of course, the degree of flexing desired can be preselected by appropriate proportioning of the length of the member 24, the thickness of the wall and the diameter of the member.

While the coupling member 24- solves the problem of shielding the electrical conductors from borehole fluids and tilting of housings relative to one another, it will be appreciated that the device thus far described may be limited in application because of the safety factor involved. That is to say, the coupling member may be broken while passing through the Well bore if subjected to an extreme bend between housing sections or parts of the tool. Hence, to improve the safety factor for the device and in furthering the aspects of this invention there is provided a tubular safety sleeve 32 which is loosely received by the coupling member 24 and is generally concentric therewith. Sleeve 32. generally limits the degree of fiexure which the coupling member may undergo to prevent breaking or incurring a permanent set in the coupling member; or, should the coupling member break, the sleeve 32 will prevent separation of adjacent housing sections. The safety sleeve 32 has barrel shaped end sections 33, 34 sized for reception Within the counter bores 26 of either housing section. The curvature of an end section 33 or 34 within the counterbored section of the housing permits pivotal movement of the safety sleeve 32 relative to the end of the housing and at the same time effectively increases the wall thickness of sleeve for strength purposes. The respective ends 33, 34 of a safety sleeve 32 are loosely connected relative to a housing by means of a pair of pins 36, 37 disposed in a plane perpendicular to the axis of the sleeve 32 and to either side of the coupling member 24. The pins 36, 37 are press fitted into openings 38 (see FIG. 3) in the housings 15, 16 with their ends suitably ground off to provide an outer surface smooth relative to a housing. The openings 40 in the sleeve 32 for the pins 36, 37 are made oversize to permit normal free or unconnected movement of the safety sleeve 32 relative to the ends of the housing 16, 17 while the coupling member 24 is flexed. It will be appreciated that should the coupling member 24 break, the pin connection between the safety sleeve 32 and housing sections 15, 16 prevents separation of the adjacent housing sections while the tool is in the tubing string. The degree of bending or fiexure is controlled by the abutment of an end surface of a housing section with the outer surface of the sleeve 32 when the housing section is tilted relative to the sleeve.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. A well tool comprising: at least two relatively rigid housing sections with hollow end portions, a tubular flexure member threadedly coupled to the respective end portions of said housings, seal means for sealing the connection between said housing sections and said fiexure member, said fiexure member having a length and cross-section sufficient to permit bending of said fiexure member in response to bending forces developed by said housing sections while said housing sections remain substantially straight, a tubular sleeve member loosely received over said fiexure member and having a diameter substantially less than the diameter of said housing sections, said sleeve member having ends sized for reception in the hollow end portions of said housing sections, and means for coupling said sleeve member to said housing sections, said sleeve member limiting the degree of bending of the flexure member.

2. A well tool particularly for use in a tubing string which has changes in inclinations comprising: at least two elongated cylindrically-shaped, relatively rigid housing sections with maximum diametrical dimensions permitting passage through a small diameter and relatively straight short section of a tubing string, said housing sections having hollow end portions arranged to face one another, a straight walled tubular fiexure and coupling member having a relatively short length as compared to said housing sections and a lesser diameter than the outer diameter of said housing sections, said straight walled fiexure member being threadedly connected to the respective hollow end portions of said housings, seal means for sealing the connection between said housing sections and said coupling member, said straight walled fiexure member having a length and cross-section sufficient to permit bending of said fiexure member in response to bending forces developed by said housing sections when passing through a change in well bore inclination, said bending forces being substantially ineffective to said housing sections so that said housing sections remain substantially straight, and longitudinally extending means coupled between ends of said housing sections for limiting the degree of fiexure of said fiexure member.

3. A well tool particularly for use in a well bore which has changes in inclinations comprising: at least three rigid housing sections including a first housing section containing electrical components, a second housing section containing radioactivity detecting means, and a third housing section containing a perforating apparatus, means to couple said housing sections to one another including hollow ends in adjacent facing housing sections, a tubular coupling member threadedly connected to the respective hollow ends of adjacent facing housing sections, seal means for sealing the connection between said housing sections and said coupling member, said tubular member having a. lesser diameter than the diameter of said housing sections and a length which is relatively short as compared to the length of said housing sections to permit fiexure of said fiexure member in response to forces developed by said housing sections when passing through a change in Well bore inclination, the interior of said coupling member being suitable for passage of electrical conductors therethrugh, a tubular sleeve member loosely received over said fiexure member and having a diameter less than the diameter of said housing sections, said sleeve member having ends sized for reception in the hollow end portions of said housing sections, means for coupling said sleeve member to said housing sections, said sleeve member limiting the degree of fiexure of said fiexure member.

4. A well tool particularly for use in a string of tubing which has changes in inclinations comprising: at least three cylindrically shaped rigid housing sections with maximum diametrical dimensions permitting passage through a small diameter and relatively straight, short section of a string of tubing, said housing sections including a first housing section containing electrical components, a second housing section containing radioactivity detecting means, and a third housing section containing a perforating apparatus, means to couple said housing sections to one another including hollow ends in adjacent facing housing sections, a straight walled tubular coupling member threadedly connected to the respective hollow ends of ad jacent facing housing sections, seal means for sealing the References Cited in the file of this patent connection between said housing sections and said cou- UNITED STATES PATENTS pling member, said straight Walled tubular member hav- Re 19,690 Hinderliter Sept. 3, 1935 ing a lesser diameter than the diameter of said housing 1,977,175 Davis 16, 1934 sections and a length which is relatively short as compared 5 2,4373 Halford 91 1948 to the length of said housing sections, to permit flexure of 2582249 Handel. 1952 2,582,746 Champion Jan. 15, 1952 sa d fleXure member In response to forces developed by 275,111 Newen et a1 July 17 1956 said housing sections when passing through a change in 2,900,023 Hams Aug 13, 1959 tubing string inclination, the interior of said coupling 10 2 9 5 031 Johns Dag 2Q, 19 0 member being suitable for passage of electrical conduc- 2,998,068 True Aug. 29, 1961 tors therethrough. 3,019,841 Tenrow Feb. 6, 1962 

2. A WELL TOOL PARTICULARLY FOR USE IN A TUBING STRING WHICH HAS CHANGES IN INCLINATIONS COMPRISING: AT LEAST TWO ELONGATED CYLINDRICALLY-SHAPED, RELATIVELY RIGID HOUSING SECTIONS WITH MAXIMUM DIAMETRICAL DIMENSIONS PERMITTING PASSAGE THROUGH A SMALL DIAMETER AND RELATIVELY STRAIGHT SHORT SECTION OF A TUBING STRING, SAID HOUSING SECTIONS HAVING HOLLOW END PORTIONS ARRANGED TO FACE ONE ANOTHER, A STRAIGHT WALLED TUBULAR FLEXURE AND COUPLING MEMBER HAVING A RELATIVELY SHORT LENGTH AS COMPARED TO SAID HOUSING SECTIONS AND A LESSER DIAMETER THAN THE OUTER DIAMETER OF SAID HOUSING SECTIONS, SAID STRAIGHT WALLED FLEXURE MEMBER BEING THREADEDLY CONNECTED TO THE RESPECTIVE HOLLOW END PORTIONS OF SAID HOUSINGS, SEAL MEANS FOR SEALING THE CONNECTION BETWEEN SAID HOUSING SECTIONS AND SAID COUPLING MEMBER, SAID STRAIGHT WALLED FLEXURE MEMBER HAVING A LENGTH AND CROSS-SECTION SUFFICIENT TO PERMIT BENDING OF SAID FLEXURE MEMBER IN RESPONSE TO BENDING FORCES DEVELOPED BY SAID HOUSING SECTIONS WHEN PASSING THROUGH A 